Experimental studies were performed to investigate the effect of Houttuyniae herba Aqua-acupuncture on the growth of Melanoma 816 tissue and Mononuclear cell subsets in mice. The results are as follows : 1. In the study of lymphocytes numbers in mice circulating blood, Houttuyniae herba Aqua-acupuncture showed inhibitory effect, but without stastistical significance. 2. In the study of $CD4^+$ T cell percentage in mice circulating blood, Houttuyniae herba Aqua-acupuncture showed inhibitory effect, but without stastistical significance. 3. In the study of $CD8^+$ T cell percentage in mice circulating blood, Houttuyniae herba Aqua-acupuncture showed inhibitory effect, with stastistical significance. 4. in the study of lymphocytes numbers in mice spleen tissue, Houttuyniae herba Aqua-acupuncture showed inhibitory effect, but without stastistical significance. 5. In the study of $CD4^+$ T cell percentage in mice spleen tissue, Houttuyniae herba Aqua-acupuncture showed inhibitory effect, but without stastistical significance. 6. In the study of $CD8^+$ T cell percentage in mice spleen tissue, Houttuyniae herba Aqua-acupuncture showed inhibitory effect, but without stastistical significance. 7. In the measurement of melanoma tissue weight, Houttuyniae herba Aqua-acupuncture showed increasing effect, but without stastistical significance. According to above results, it is concluded that Houttuyniae herba Aqua-acupuncture is effective upon immune responses in Melanoma 816 inoculated mice.